Semiconductors and other electronic components need to be interconnected with each other to form circuits. As semiconductors continue to improve in performance, cost, reliability and miniaturization, there is an intensive need in the electronics industry to package and interconnect these semiconductors without limiting system performance. One approach in patterning metal lines on a substrate is the well-known photolithography technique. Although conventional photolithography is widely employed in the formation of patterns on a substrate, photolithography not only requires expensive chemicals and aligners/steppers, but also is typically the most time consuming and labor intensive step. Additionally, traditional photolithography optical aligners require very flat substrates due to the small depth of focus. This becomes an increasingly major drawback as larger substrates are used.
Various methods have been developed to overcome the drawbacks of photolithography and these methods relate to developing several maskless (or re-usable mask) techniques to direct-write metal lines and features on substrates. Such techniques include ink jet printing, offset printing, liquid metal ion sources, liquid metal cluster sources, laser direct-write, chemical vapor deposition, and electron-beam enhanced deposition, among others. Although these techniques have matured into relatively reliable processes, at present, none of these techniques have been widely accepted for manufacturing. Drawbacks arising from these techniques include low throughput, poor adhesion, high resistivity, high contact resistance, and poor resolution, among others.
Accordingly, there is a need for a method and apparatus for forming high resolution patterns on the surface of semiconductor substrates without requiring the use of photolithography. Also needed is a method and apparatus for forming high resolution patterns to achieve a very high packing density within a single IC chip.